Re: [OFFTOPIC] Re: [?] Why should Distros be called as i386 for a 32-bit PC, and as amd64 for a 64-bit PC, when Intel Core PCs are also 64bit systems

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> The original plan/claims was that the support for legacy i386
>> application would be "just as fast".  This never materialized
>> (unsurprisingly: it's easy to make a CPU that can run efficiency several
>> slightly different instruction sets (ISA), like your average amd64 CPU which
>> can run applications using the amd64 ISA, the i386 ISA, the 80286 ISA
>> or the 8086 ISA, more or less; but it's much harder to make a CPU that
>> can run efficiently very different ISAs).
> Apple seems to be doing quite well with the M1.

But that's not a CPU that runs amd64 code: the amd64 code is executed on
it by software emulation rather than by hardware emulation.  And indeed,
Intel could have developed an efficient software emulation of amd64 for
its Itanium which could have been more efficient than its own
hardware emulator.

[ Similarly, at some point in time, DEC's Alpha was claimed to be the
  fastest processor to run i386 code, via its software emulation. ;-)  ]

Apple has a lot of experience in that kind of emulation (having done it
for the transition from Motorola's 68K to PowerPC, then again from
PowerPC to i386, and now from amd64 to ARM (notice they relied on
hardware emulation for the i386 to amd64 transition)).

But note that they only do emulation for applications AFAIK, which is
easier than doing a "full" emulation that lets you run an actual OS
(like `qemu` does).

> There's already work in progress to port Linux mainline (and 
> consequently Debian) to the Apple M1 :)

Since the M1 implements the ARM instruction set, I don't think there's
much work to do here, indeed (most likely the hardest part is to fight
Apple's opaqueness).

Last I heard Debian works on the M1 already :-), but its Emacs package
doesn't :-(


        Stefan